Perlecan is a specific heparan sulfate proteoglycan (HSPG) and a common constituent of all amyloid deposits regardless of the specific amyloid protein involved. Perlecan is believed to play primary roles in the pathogenesis of amyloidosis and contributes to the formation, deposition, accumulation and/or persistence of amyloid in a variety of tissues and in different clinical settings.
However, perlecan is an extremely difficult macromolecule to isolate in pure form, especially in substantial quantities, due in part to perlecan's inherent ability to interact with a number of different proteins and macromolecules. The most commonly utilized extract source for isolation of perlecan is the Engelbreth-Holm-Swarm (EHS) tumor which is routinely grown in the hind legs of mice. However, major problems still exist with trying to obtain “clean” perlecan from this basement membrane producing tumor, especially when using known methods of isolation. These problems include: a) contamination by other proteins and/or basement membrane components of the EHS tumor including laminin, fibronectin and type IV collagen which all tend to interact with perlecan, b) contamination due to the presence of free glycosaminoglycan (GAG) chains, and c) degradation of the perlecan core protein.
Thus, there is a need in the art to develop effective new ways to isolate perlecan in high yield and of high quality (i.e. “clean” or substantially “pure” perlecan) in order to use this product for a number of important biological assays which have impact on a number of major human diseases including Alzheimer's disease, Down's syndrome, type II diabetes, certain forms of cancer and inflammatory disorders. All of these latter diseases involve amyloid accumulation and persistence, and involve perlecan and related HSPGs in the pathogenesis. Isolation of perlecan for use in further understanding perlecan's role in the pathogenesis of these major human disorders and for the eventual identification of new therapeutics will be of tremendous benefit.